Swartchild Black Shield Mainspring for Hampden 8/0s #15696 - Steel

Swartchild & Co Black Shield Mainspring No.440661 for Hampden 8/0s movements, Factory No. 15696, steel, new in envelope. Swartchild Mainspring Catalog (which I sell) lists this as a Dennison 3½ x 8 ½ . See images for further details. I likely have several of these so the one you get may differ slightly from the images. I specialize in hard to find watch parts and all watch parts are unconditionally guaranteed. Images do a pretty good job of representing the item.